A requirement that is becoming increasingly important in respect of adhesives is that they not only have good bonding properties but are also biodegradable. However, the known adhesives do not meet this requirement to a sufficient extent: powerful adhesives are generally not biodegradable or are biodegradable to only a slight extent.
An adhesive layer that contains a copolymer of an abietinoyl-glyceryl(meth)acrylate, an alkyl acrylate and a polyethylene glycol(meth)acrylate is described in European Patent EP 0 745 653. The adhesives concerned here are contact adhesives and not construction adhesives. There is also no mention of any biodegradability of the adhesive layers.
Netherlands Patent Application 9201695 (patent number 195014) corresponding to U.S. Pat. No. 5,580,940 discloses a biodegradable diacrylate with a sugar as central unit. These known diacrylates comply, for example, with the formula:(H2C═C(R)—CO—O—A—O—CO—NH—Y—NH—CO—O)mZwherein A is a C2–C4 alkylene group, R is hydrogen or methyl, Y is an alicyclic group, in particular an isophoronediyl group and Z is a sugar residue, such as a glucose or fructose residue. As a result of the sugar residue, too high a solubility in water is produced, as a result of which the polymer is less suitable for construction adhesives for metal, plastic, glass and wood, The size of the side groups (isophoronediyl and sugar) on the reactive acrylate also means that the polymer will be weak and soft, which is very suitable for paper and cardboard and for contact adhesives, but not for construction adhesives.
In the known products, insofar as they are biodegradable adhesives, the adhesive characteristics are inadequate for construction adhesives and the application possibilities are restricted.